Radiocommunication networks were originally developed primarily to provide voice services over circuit-switched networks. The introduction of packet-switched bearers in, for example, the so-called 2.5 generation (G) and 3G networks enabled network operators to provide data services as well as voice services. Eventually, network architectures will likely evolve toward all Internet Protocol (IP) networks which provide both voice and data services. However, network operators have a substantial investment in existing infrastructures and would, therefore, typically prefer to migrate gradually to all IP network architectures in order to allow them to extract sufficient value from their investment in existing infrastructures. Also to provide the capabilities needed to support next generation radiocommunication applications, while at the same time using legacy infrastructure, network operators could deploy hybrid networks wherein a next generation radiocommunication system is overlaid onto an existing circuit-switched or packet-switched network as a first step in the transition to an all IP-based network. Alternatively, a radiocommunication system can evolve from one generation to the next while still providing backward compatibility for legacy equipment.
Specification is ongoing in 3GPP for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) that is the next generation of Radio Access Network (RAN). Another name for E-UTRAN, used in the present specification, is Long Term Evolution (LTE) RAN. The core network to which E-UTRAN is connected is called Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) network. Both the E-UTRAN and the EPC (and possibly some other node(s), such as the Home Subscriber Server (HSS), depending on the definition of the EPC) comprise together the Evolved Packet System (EPS), which is also known as the SAE/LTE network. A base station in this concept is called an E-UTRAN NodeB (eNodeB or eNB). These ongoing studies also include the possibility to have an E-UTRAN base station which provides home or small area coverage for a limited number of users. This base station is, in 3GPP and in this document, called a Home E-UTRAN NodeB (HeNB) or home base station. Other names used for this type of base station are LTE Home Access Point (LTE HAP) and LTE Femto Access Point (LTE FAP).
The HeNB would typically provide regular service for the end users and would be connected to the mobile core network using an IP-based transmission link. The radio service coverage provided by an HeNB is called a femtocell in this application. Furthermore, a femtocell is normally a Closed Subscriber Group (CSG) cell, i.e., a cell in which only a limited set of users is normally allowed to access the network. The HeNB would, in most cases, use the end user's already existing broadband connection (e.g. xDSL and Cable) to achieve connectivity to the operator's mobile Core Network (CN) and possibly to other eNBs/HeNBs. One of the main reasons for providing wireless local access using HeNBs and femtocells is to provide cheaper calls or transaction rates/charges when a device (e.g., a mobile phone) is connected via an HeNB as compared to when that device is connected via an eNB.
More generally, an HeNB and similar devices can be considered to be a sort of “home base station”. As used herein, the term “home” is used to modify the phrase “base station” to distinguish such equipment from other conventional base stations based upon characteristics such as one or more of: (I) geographic radio coverage provided (i.e., home base station coverage area is normally less than “regular” base station coverage area), (2) subscriber access (i.e., the subscribers who can obtain service from the home base station may be limited whereas a “regular” base station will typically provide access to any subscribers (or at least to a larger group of subscribers than a home base station) who are within range, and (3) home base stations are normally installed by the end users themselves without any intervention from the operator's personnel, whereas regular base stations are typically installed by operator personnel. This latter quality of home base stations suggests that the installation will generally be highly automated and of a “plug and play” nature. Note, however, that home bases stations need not literally be installed in personal residences, and may find applications in businesses, public areas, etc., wherein the qualities of a home base station are desirable to, e.g., supplement coverage provided by regular base stations. Home gateways, as the phrase is used herein, are gateways which interface home base stations with a node in the radiocommunication system, e.g., a core network node.
It is envisioned that a mobile radiocommunication network which implements this type of architecture may have several hundreds of thousands or even a million or more HeNBs or other types of home base stations connected thereto. Such a large number of access points will present various challenges relating to their connections to the core network. Accordingly, it would be desirable to have methods and systems which address core network node selection challenges/issues such as those posed by the introduction of home base stations.